Will Tomorrow's Supercomputers Be Superconducting?

Today, the list of the 500 fastest supercomputers is dominated by computers based on semiconducting circuitry. Ten years from now, will superconducting computers start to take some of those slots?

Last week, IARPA, the U.S. intelligence community’s high-risk research arm, announced that it had awarded its first set of research contracts in a multi-year effort to develop a superconducting computer. The program, called Cryogenic Computing Complexity (C3), is designed to develop the components needed to construct such a computer as well as a working prototype.

Northrop Grumman is one of the awardees, along with IBM and Raytheon-BBN, in the first phase of IARPA’s C3 project.

If the program succeeds, it could potentially be a big boon to the makers of supercomputers. The ubiquitous CMOS-based technology we use to make those systems is proving difficult to scale up without consuming staggering amounts of power.

Superconducting circuitry, which boasts resistance-less wires and hyper-fast switches, could potentially be a faster and more efficient alternative – even when you take into account the fact that it will require cryocoolers to take the temperature down to a few degrees above absolute zero.

The idea of superconducting computing actually extends all the way back to the dawn of the computer age. One of the early candidates for digital logic was a superconducting switch called a cryotron, developed in the 1950’s by engineer Dudley Buck.

This time around, the leading logic candidate is likely to be a form of single-flux quantum (SFQ) circuitry. SFQ logic is based on flow: bits stream through the circuits as voltage pulses, which are blocked or passed by superconducting devices called Josephson junctions. A bit is 0 or 1 depending on whether a pulse is present or not during a given period of time.

I wrote about this form of logic a few years back, when a team at Northrop Grumman reported a new, lower-power incarnation of the technology. In fact, Northrop Grumman is one of the awardees, along with IBM and Raytheon-BBN, in the first phase of IARPA’s C3 project.

This first phase, according to program documents (pdf) released last year, will focus on demonstrating critical superconducting computing components. Two projects will focus on logic and two on memory, C3 program manager Marc Manheimer recently told HPCwire. In phase two, the components will be combined to create a working computer.

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